Audio amplifiers and speakers for entertainment systems can take a variety of forms. In one case, musical instruments generate electrical audio signals representative of sounds produced by the instrument. Electric guitars and electric bass guitars are well-known musical instruments. The artist plays the guitar and generates electric signals representative of the intended notes and chords. In another case, the audio signals may be generated from vocals through a microphone. The electrical signals are routed through one or more audio amplifiers for pre-amplification, power amplification, filtering, and other signal processing to enhance the tonal quality and properties of the signal. The processed signals then drive one or more speaker systems to reproduce the original sound from the musical instrument for the audience.
FIG. 1 illustrates a conventional musical instrument 10, such as an electric bass guitar, providing electrical signals to audio amplifier 12. In one embodiment, audio amplifier 12 can be implemented as ICE Power 250ASX2 audio power amplifier. Other signal processing units 14, such as pre-amplifier or effects loop, can be placed between musical instrument 10 and audio amplifier circuit 12. Audio amplifier 12 has separate outputs to drive one or two speaker systems 16 and 18, such as passive or active speakers, subwoofers, wireless speakers, multimedia audio, and distributed audio. Audio amplifier 12 is typically housed in a compact, small profile case having dimensions of 6.4×25.4×26.7 centimeters (cm) and weight of about 1.7 kilograms. Audio amplifier 12 can produce 250 watts (W) into two 4-ohm loads for stereo applications, or 500 W into a single 8-ohm load using a bridge tied load (BTL) for mono applications. Amplifier is specified for convection cooled operation, and the amplifier is not rated for 2 ohm stereo or 4 ohms BTL operation.
Musicians often demand additional power depending on the type of music being played. Although more power can be generated by physically larger units, the competitive market prefers the compact case due to its light weight and convenience of handling. Yet, an attempt to generate more power from the compact case tends to increase heat dissipation and operating currents. The compact case cannot properly dissipate the heat generated by higher power ratings of 2 ohm stereo or 4 ohm BTL operation. The tradeoff between power, thermal management, and size of the amplifier case has limited conventional audio amplifiers to the specifications described above.